/* ============================================================
   PostureIQ — Stylesheet
   Color Palette:
     --navy:    #0B1A2B  (deep navy)
     --navy-l:  #1A2D45  (lighter navy)
     --white:   #FFFFFF
     --accent:  #00D4FF  (electric blue)
     --accent-d:#00B4D8  (accent darker, hover)
     --gray:    #8899AA  (muted text)
     --bg:      #060F1A  (background)
   ============================================================ */

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --navy: #0B1A2B;
  --navy-l: #1A2D45;
  --white: #FFFFFF;
  --accent: #00D4FF;
  --accent-d: #00B4D8;
  --gray: #8899AA;
  --bg: #060F1A;
  --font: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.6;
  color: var(--white);
  background: var(--bg);
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color var(--transition);
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

/* ---------- Utility ---------- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

.container--narrow {
  max-width: 800px;
}

.text-accent {
  color: var(--accent);
}

.muted {
  opacity: 0.5;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 32px;
  font-family: var(--font);
  font-size: 0.95rem;
  font-weight: 600;
  border: 2px solid transparent;
  border-radius: 50px;
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn--primary {
  background: var(--accent);
  color: var(--navy);
  border-color: var(--accent);
}

.btn--primary:hover {
  background: var(--accent-d);
  border-color: var(--accent-d);
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(0, 212, 255, 0.3);
}

.btn--outline {
  background: transparent;
  color: var(--white);
  border-color: rgba(255, 255, 255, 0.25);
}

.btn--outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.btn--lg {
  padding: 18px 40px;
  font-size: 1.05rem;
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  padding: 16px 0;
  transition: all var(--transition);
}

.nav--scrolled {
  background: rgba(6, 15, 26, 0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: 10px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
}

.nav__container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav__link {
  font-size: 0.875rem;
  font-weight: 500;
  color: rgba(255, 255, 255, 0.7);
  transition: color var(--transition);
}

.nav__link:hover {
  color: var(--white);
}

.nav__link--muted {
  opacity: 0.4;
}

.nav__btn {
  font-size: 0.875rem;
  font-weight: 600;
  padding: 8px 20px;
  border-radius: 50px;
  border: 2px solid transparent;
  transition: all var(--transition);
}

.nav__btn--ghost {
  color: rgba(255, 255, 255, 0.7);
}

.nav__btn--ghost:hover {
  color: var(--white);
}

.nav__btn--primary {
  background: var(--accent);
  color: var(--navy);
  border-color: var(--accent);
}

.nav__btn--primary:hover {
  background: var(--accent-d);
  border-color: var(--accent-d);
}

.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav__hamburger span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--white);
  border-radius: 2px;
  transition: all var(--transition);
}

.nav__hamburger.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav__hamburger.active span:nth-child(2) {
  opacity: 0;
}

.nav__hamburger.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 120px 0 80px;
  overflow: hidden;
}

.hero__container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero__tag {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(0, 212, 255, 0.1);
  border: 1px solid rgba(0, 212, 255, 0.2);
  border-radius: 50px;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.hero__title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 24px;
}

.hero__subtitle {
  font-size: 1.125rem;
  color: var(--gray);
  max-width: 520px;
  margin-bottom: 36px;
  line-height: 1.7;
}

.hero__actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.hero__proof {
  display: flex;
  gap: 40px;
}

.hero__stat strong {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
}

.hero__stat span {
  font-size: 0.8rem;
  color: var(--gray);
}

/* Hero device illustration */
.hero__visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero__device {
  width: 280px;
  height: 400px;
  background: linear-gradient(145deg, var(--navy-l), var(--navy));
  border-radius: 32px;
  border: 1px solid rgba(0, 212, 255, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  box-shadow:
    0 0 80px rgba(0, 212, 255, 0.08),
    0 40px 80px rgba(0, 0, 0, 0.4);
}

.hero__device::before {
  content: '';
  position: absolute;
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 4px;
}

.hero__device-screen {
  text-align: center;
}

.hero__spine {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  margin-bottom: 30px;
}

.hero__spine-node {
  width: 12px;
  height: 12px;
  background: var(--accent);
  border-radius: 50%;
  position: relative;
  animation: spine-pulse 2s ease-in-out infinite;
}

.hero__spine-node::after {
  content: '';
  position: absolute;
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 2px;
  height: 14px;
  background: rgba(0, 212, 255, 0.3);
}

.hero__spine-node:last-child::after {
  display: none;
}

.hero__spine-node:nth-child(2) { animation-delay: 0.1s; }
.hero__spine-node:nth-child(3) { animation-delay: 0.2s; }
.hero__spine-node:nth-child(4) { animation-delay: 0.3s; }
.hero__spine-node:nth-child(5) { animation-delay: 0.4s; }
.hero__spine-node:nth-child(6) { animation-delay: 0.5s; }
.hero__spine-node:nth-child(7) { animation-delay: 0.6s; }

@keyframes spine-pulse {
  0%, 100% { opacity: 0.5; transform: scale(1); }
  50% { opacity: 1; transform: scale(1.2); }
}

.hero__device-label {
  font-size: 0.75rem;
  color: var(--gray);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 4px;
}

.hero__device-score {
  font-size: 3rem;
  font-weight: 800;
  color: var(--accent);
}

.hero__gradient {
  position: absolute;
  top: -20%;
  right: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(0, 212, 255, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

/* ---------- Sections (shared) ---------- */
.section {
  padding: 100px 0;
}

.section__header {
  text-align: center;
  max-width: 640px;
  margin: 0 auto 64px;
}

.section__tag {
  display: inline-block;
  padding: 4px 14px;
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.15);
  border-radius: 50px;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.section__title {
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.section__subtitle {
  font-size: 1.05rem;
  color: var(--gray);
  line-height: 1.7;
}

/* ---------- About ---------- */
.about__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.about__card {
  background: linear-gradient(145deg, rgba(26, 45, 69, 0.5), rgba(11, 26, 43, 0.8));
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius);
  padding: 40px 32px;
  transition: all var(--transition);
}

.about__card:hover {
  border-color: rgba(0, 212, 255, 0.2);
  transform: translateY(-4px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.about__card-icon {
  margin-bottom: 20px;
}

.about__card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.about__card p {
  font-size: 0.925rem;
  color: var(--gray);
  line-height: 1.7;
}

/* ---------- How It Works ---------- */
.how {
  background: linear-gradient(180deg, var(--bg) 0%, rgba(26, 45, 69, 0.15) 50%, var(--bg) 100%);
}

.how__steps {
  display: flex;
  flex-direction: column;
  gap: 24px;
  max-width: 900px;
  margin: 0 auto;
}

.how__step {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: 32px;
  align-items: center;
  background: rgba(26, 45, 69, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius);
  padding: 40px;
  transition: all var(--transition);
}

.how__step:hover {
  border-color: rgba(0, 212, 255, 0.15);
  background: rgba(26, 45, 69, 0.5);
}

.how__step-number {
  font-size: 3rem;
  font-weight: 800;
  color: rgba(0, 212, 255, 0.15);
  line-height: 1;
  min-width: 80px;
}

.how__step-content h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.how__step-content p {
  font-size: 0.925rem;
  color: var(--gray);
  line-height: 1.7;
}

.how__step-visual {
  opacity: 0.6;
}

/* ---------- Benefits ---------- */
.benefits__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.benefits__card {
  padding: 36px 28px;
  background: rgba(26, 45, 69, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.benefits__card:hover {
  border-color: rgba(0, 212, 255, 0.15);
  transform: translateY(-4px);
}

.benefits__icon {
  margin-bottom: 20px;
}

.benefits__card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.benefits__card p {
  font-size: 0.9rem;
  color: var(--gray);
  line-height: 1.7;
}

/* ---------- Audience ---------- */
.audience {
  background: linear-gradient(180deg, var(--bg) 0%, rgba(26, 45, 69, 0.15) 50%, var(--bg) 100%);
}

.audience__grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.audience__card {
  text-align: center;
  padding: 44px 24px;
  background: rgba(26, 45, 69, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.audience__card:hover {
  border-color: rgba(0, 212, 255, 0.2);
  transform: translateY(-6px);
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.audience__emoji {
  margin-bottom: 20px;
  display: flex;
  justify-content: center;
}

.audience__card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.audience__card p {
  font-size: 0.875rem;
  color: var(--gray);
  line-height: 1.7;
}

/* ---------- FAQ ---------- */
.faq__list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq__item {
  background: rgba(26, 45, 69, 0.3);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color var(--transition);
}

.faq__item[open] {
  border-color: rgba(0, 212, 255, 0.15);
}

.faq__question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1rem;
  list-style: none;
  user-select: none;
  transition: color var(--transition);
}

.faq__question::-webkit-details-marker {
  display: none;
}

.faq__question:hover {
  color: var(--accent);
}

.faq__chevron {
  flex-shrink: 0;
  transition: transform var(--transition);
}

.faq__item[open] .faq__chevron {
  transform: rotate(180deg);
}

.faq__answer {
  padding: 0 24px 20px;
}

.faq__answer p {
  font-size: 0.925rem;
  color: var(--gray);
  line-height: 1.7;
}

/* ---------- CTA ---------- */
.cta {
  text-align: center;
  padding: 80px 0;
}

.cta__title {
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.cta__subtitle {
  font-size: 1.1rem;
  color: var(--gray);
  max-width: 500px;
  margin: 0 auto 36px;
  line-height: 1.7;
}

.cta__actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ---------- Footer ---------- */
.footer {
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  padding: 64px 0 32px;
}

.footer__grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.5fr;
  gap: 40px;
  margin-bottom: 48px;
}

.footer__brand .nav__logo {
  margin-bottom: 12px;
}

.footer__tagline {
  font-size: 0.875rem;
  color: var(--gray);
  max-width: 260px;
  line-height: 1.6;
}

.footer__col h4 {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 16px;
  color: rgba(255, 255, 255, 0.8);
}

.footer__col ul li {
  margin-bottom: 10px;
}

.footer__col ul a {
  font-size: 0.875rem;
  color: var(--gray);
  transition: color var(--transition);
}

.footer__col ul a:hover {
  color: var(--white);
}

.footer__newsletter p {
  font-size: 0.875rem;
  color: var(--gray);
  margin-bottom: 16px;
  line-height: 1.6;
}

.footer__form {
  display: flex;
  gap: 8px;
}

.footer__form input {
  flex: 1;
  min-width: 0;
  padding: 12px 16px;
  font-family: var(--font);
  font-size: 0.875rem;
  background: rgba(26, 45, 69, 0.5);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: 50px;
  color: var(--white);
  outline: none;
  transition: border-color var(--transition);
}

.footer__form input::placeholder {
  color: var(--gray);
}

.footer__form input:focus {
  border-color: var(--accent);
}

.footer__form .btn {
  padding: 12px 24px;
  font-size: 0.85rem;
  flex-shrink: 0;
}

.footer__bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 32px;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer__bottom p {
  font-size: 0.8rem;
  color: var(--gray);
}

.footer__social {
  display: flex;
  gap: 16px;
}

.footer__social a {
  color: var(--gray);
  transition: color var(--transition);
}

.footer__social a:hover {
  color: var(--accent);
}

/* ---------- Modal (placeholder) ---------- */
.modal {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition);
}

.modal--open {
  opacity: 1;
  pointer-events: auto;
}

.modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
}

.modal__content {
  position: relative;
  background: var(--navy-l);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
  padding: 48px;
  max-width: 440px;
  width: 90%;
  text-align: center;
  transform: translateY(20px);
  transition: transform var(--transition);
}

.modal--open .modal__content {
  transform: translateY(0);
}

.modal__content h3 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.modal__content p {
  font-size: 0.925rem;
  color: var(--gray);
  margin-bottom: 24px;
  line-height: 1.6;
}

.modal__close {
  position: absolute;
  top: 16px;
  right: 16px;
  background: none;
  border: none;
  color: var(--gray);
  font-size: 1.5rem;
  cursor: pointer;
  transition: color var(--transition);
  line-height: 1;
}

.modal__close:hover {
  color: var(--white);
}

/* ---------- Fade-in Animation ---------- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.fade-in--delay {
  transition-delay: 0.2s;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ---------- Responsive ---------- */

/* Tablet */
@media (max-width: 1024px) {
  .hero__container {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 40px;
  }

  .hero__subtitle {
    margin-left: auto;
    margin-right: auto;
  }

  .hero__actions {
    justify-content: center;
  }

  .hero__proof {
    justify-content: center;
  }

  .about__grid {
    grid-template-columns: 1fr;
    max-width: 520px;
    margin: 0 auto;
  }

  .audience__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .benefits__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .how__step {
    grid-template-columns: auto 1fr;
    gap: 24px;
  }

  .how__step-visual {
    display: none;
  }
}

/* Mobile */
@media (max-width: 768px) {
  .nav__links {
    position: fixed;
    top: 0;
    right: 0;
    width: 280px;
    height: 100vh;
    flex-direction: column;
    align-items: flex-start;
    justify-content: center;
    gap: 20px;
    padding: 40px;
    background: rgba(6, 15, 26, 0.98);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-left: 1px solid rgba(255, 255, 255, 0.06);
    transform: translateX(100%);
    transition: transform var(--transition);
  }

  .nav__links.open {
    transform: translateX(0);
  }

  .nav__hamburger {
    display: flex;
  }

  .section {
    padding: 72px 0;
  }

  .hero {
    padding: 100px 0 60px;
    min-height: auto;
  }

  .hero__device {
    width: 220px;
    height: 320px;
  }

  .hero__proof {
    flex-direction: column;
    gap: 16px;
    align-items: center;
  }

  .about__grid {
    grid-template-columns: 1fr;
  }

  .benefits__grid {
    grid-template-columns: 1fr;
  }

  .audience__grid {
    grid-template-columns: 1fr;
  }

  .how__step {
    grid-template-columns: 1fr;
    text-align: center;
    padding: 28px;
  }

  .how__step-number {
    font-size: 2rem;
    min-width: auto;
  }

  .footer__grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .footer__form {
    flex-direction: column;
  }

  .footer__bottom {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
}

/* Small mobile */
@media (max-width: 480px) {
  .hero__title {
    font-size: 2rem;
  }

  .hero__actions {
    flex-direction: column;
    align-items: center;
  }

  .btn--lg {
    width: 100%;
    justify-content: center;
  }
}